Clara Parejo Farnés, University of Seville. Supervisors: A. Aparicio and RG. Albaladejo. February 2018.
Summary:
Seed dispersal is capital for the demography and
population genetics of seed plant populations since it constitutes the
initial template for natural regeneration and the spatial genetic
structure of the adult population. Habitat loss and fragmentation might
determine the composition and behaviour of avian seed dispersers and the
outcome of dispersal through several non mutually exclusive causes:
demographic limitation (if seed production is scarce), distance
limitation (if dispersers do not carry seeds far away), ecological
limitation (if seeds are only transported to specific microhabitats),
and maternal limitation (if dispersers only feed on a few preferred
mother plants). Thus, assessing the quantity and the genetic composition
of the propagules in the seed rain becomes crucial to understand the
fate of species whose seeds are exclusively bird dispersed.
The comprehensive objective in this thesis is to assess the quantity,
the spatial distribution, the effective contribution of parental and
maternal plants separately (DNA from the endocarp of naturally dispersed
seedling can be readily studied) in Pistacia lentiscus a
key-stone Mediterranean dioecious species. Necessarily, we are
characterizing the composition and behaviour (disperser vs. predator) of
the avian community and quantifying the seed rain at two contrasting
scales: a fine scale of diverse microhabitats within fragments, and the
landscape scale (considering isolated vs continuous and small vs. large
woodland fragments). Finally, we are studying if dispersal can also be
limited by the heritage of genetic material modified by the stressing
environmental conditions of maternal plants (lets say, epigenetic
limitation).